The U.S. unemployment rate has drop to the lowest levels in two years, according to data released today by the Bureau of Labor Statistics. Although unemployment rates for Black, Latino and young individuals remain higher than average, those rates have also continued to drop to low levels since 2012.

The dropping unemployment rates do not tell the entire story of the U.S. labor force. Many workers are leaving, whether retiring or becoming discouraged after too long spent unemployed. Since last year, an additional two million adults left the labor force while just 62,000 joined it. 

Many workers may not be unemployed, but still remain under-employed, like the 7.5 million workers who work part-time, not by choice, but because of economic conditions. Another 18.9 million, the same number as a year ago, work part-time for noneconomic reasons.

Growing childcare costs and slow job growth in many states could be reasons that individuals are leaving the workforce or still struggling to re-enter.